a) Field of the Invention
The invention relates to a substrate with multi-layer interconnection structure, methods of manufacturing and recycling such substrate, a method of packaging electronic devices by using such substrate, and a method of manufacturing multi-layer interconnection devices, and more particularly, to a substrate with multi-layer interconnection structure, wherein the multi-layer interconnection structure is adhered to the substrate in partial areas, and methods of manufacturing and recycling such substrate, a method of packaging electronic devices by using such substrate, and a method of manufacturing multi-layer interconnection devices.
b) Description of the Related Art
With the advancement of semi-conductor manufacturing technology, the line width, line spacing, and size of chips become smaller and smaller, and the chips require faster transmission speed and higher output efficiency. In response thereto, better packaging technology of electrically connecting the chips to the exterior is required, wherein more wires are needed and wire spacing is smaller, and thus the technology of chip packaging slowly transforms from through hole type to surface mount type, and from connecting by gold wire in wiring frames to connecting by bumps, and circuit boards transform from hard printed circuit board (PCB), flexible printed circuit board (FPC), to integrated circuit board (IC).
In general, a hard PCB with six layers of BT material weighs about 4 grams and has a thickness of about 1 mm, and therefore it cannot be bent; on the other hand, a FPC board with a thickness of about 50 .mu.m can only make two layers of interconnection. On the contrary, an IC board with a thickness of about 50 .mu.m can be manufactured into a substrate with six layers of interconnection that weigh about 0.21 grams in total, and so the IC board has the best flexibility and is the most compact. Moreover, in regard to interconnection density, the minimum diameter of the through holes of the hard PCB and the FPC board is 50 .mu.m, the minimum dimension of the through hole bonding pads of the hard PCB and the FPC board is 100 .mu.m, and the minimum line width and the minimum line spacing are 25 .mu.m. In contrast, the minimum diameter of through holes of the IC board is 20 .mu.m, its minimum through hold bonding pad is 25 .mu.m, and the minimum line width and minimum line spacing are 20 .mu.m; hence, the IC board greatly increases the density of interconnection.
The miniaturization of circuit board sizes causes the request of circuit board precision to increase, so the manufacturing process of circuit boards faces new challenges, especially the challenge of how to increase the wiring density in the manufacturing process is very important, and the key to increase the wiring density is the stability of circuit board size in the manufacturing process. A conventional solution is to manufacture IC boards on a hard substrate, which uses the better size stability of the substrate to increase the size stability of the IC board during the process, however, how to separate the IC board and the substrate after the fabrication of IC board is complete is a major issue for this type of technology.
U.S. Pat. No. 4,812,191 discloses a method of manufacturing multi-layer interconnection structure by using a sacrificial substrate fabrication technique, wherein a multi-layer interconnection structure is formed on a substrate that has a smaller coefficient of thermal expansion than that of the multi-layer interconnection, and then the temperature is elevated to perform curing, after which the temperature is lowered to generate enough tension between the substrate and the multi-layer interconnection structure before the multi-layer interconnection structure is separated from the substrate by adhering a support device to the multi-layer interconnection structure and by acid-immersion.
U.S. Pat. No. 5,258,236 discloses a method for separating substrate and multi-layer interconnection structure by using laser ablation. First, a polymer layer 2, a metal layer 3, and a multi-layer interconnection structure 4 are sequentially formed on a transparent substrate 1 as shown in FIG. 1; second, a laser ultraviolet light is irradiated on the polymer layer 2 through the transparent substrate 1 to dissolve the polymer layer 2 so that the transparent substrate 1 can be removed from the rest of the structure.
However, the aforementioned separation method is more complicated, thus, how to provide a method and structure that can manufacture IC boards with high size precision and can separate the IC board and the substrate in an easy and low cost way is the goal to be achieved by the circuit board manufacturing industry.